This invention relates to governor operation for a fuel injection pump or the like, and most particularly, to apparatus for providing selective adjustment of the main governor spring of such a governor.
In the use of a fuel injection pump for an engine or the like, it is well known to provide a governor having interacting springs and fly-weight means (see, for example, U.S. Pat. No. 3,915,140 to Parks et al, assigned to the assignee of this invention). The operating characteristics of the engine are to an extent dependent on the characteristics of the main governor spring in such a system. For example, a main governor spring with a relatively high spring rate will provide less governor sensitivity while providing a relatively high "speed droop" characteristic, fully described in U.S. Pat. No. 3,915,140, cited above. Conversely, providing the main governor spring to be of a relatively lower spring rate tends to increase the sensitivity of the operation of the governor, while decreasing speed droop.
Depending on the desired operating characteristics of the engine, it will therefore be understood that under such varying conditions, it is desirable to provide that the main governor spring be of relatively higher or lower spring rate.